From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Balbi Subject: Re: [PATCH] cbus-tahvo: Add tahvo_write_reg locking Date: Mon, 7 Nov 2011 11:27:32 +0200 Message-ID: <20111107092731.GE4265@legolas.emea.dhcp.ti.com> References: <20111105171954.230d12fb@milhouse> <20111107061044.GB4265@legolas.emea.dhcp.ti.com> <20111107091836.61377657@Nokia-N900> Reply-To: balbi@ti.com Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="qOrJKOH36bD5yhNe" Return-path: Received: from na3sys009aog124.obsmtp.com ([74.125.149.151]:41347 "EHLO na3sys009aog124.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734Ab1KGJ1j (ORCPT ); Mon, 7 Nov 2011 04:27:39 -0500 Received: by bkbzs2 with SMTP id zs2so195712bkb.6 for ; Mon, 07 Nov 2011 01:27:36 -0800 (PST) Content-Disposition: inline In-Reply-To: <20111107091836.61377657@Nokia-N900> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Michael =?iso-8859-1?Q?B=FCsch?= Cc: balbi@ti.com, Tony Lindgren , linux-omap --qOrJKOH36bD5yhNe Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Mon, Nov 07, 2011 at 09:18:36AM +0000, Michael B=FCsch wrote: > > On Sat, Nov 05, 2011 at 05:19:54PM +0100, Michael B=FCsch wrote: > > > tahvo_write_reg() needs to take the mutex to avoid a race > > > condition with tahvo_set_clear_reg_bits: > > >=20 > > > tahvo_set_clear_reg_bits(): | tahvo_write_reg(): > > > __tahvo_read_reg() | > > > | __tahvo_write_reg() <-- race here > > > __tahvo_write_reg() | > > >=20 > > > Signed-off-by: Michael Buesch > > >=20 > > > --- > > >=20 > > > Index: linux-3.1/drivers/cbus/tahvo.c > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > > --- linux-3.1.orig/drivers/cbus/tahvo.c 2011-11-05 17:03:39.598846119= +0100 > > > +++ linux-3.1/drivers/cbus/tahvo.c 2011-11-05 17:04:36.274768324 +0100 > > > @@ -104,7 +104,9 @@ void tahvo_write_reg(struct device *chil > > > { > > > struct tahvo *tahvo =3D dev_get_drvdata(child->parent); > > > =20 > > > + mutex_lock(&tahvo->mutex); > > > __tahvo_write_reg(tahvo, reg, val); > > > + mutex_unlock(&tahvo->mutex); > >=20 > > yeah, my bad. The same should be done with tahvo_read_reg(). Care to > > resend this patch adding the change to tahvo_read_reg() too... >=20 > I think tahvo_read_reg is fine without a lock. > read vs write is already atomic due to the cbus lock. >=20 > it's the same situation as for retu. where we also don't need the lock > in retu_read_reg. ok then, makes sense. FWIW: Acked-by: Felipe Balbi --=20 balbi --qOrJKOH36bD5yhNe Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJOt6SDAAoJEIaOsuA1yqREPckP/3pENS7v9rIC7r4Y+TnCmTYQ K/yPJI1e2YW6rtB5hsH5uKN5jyXYBEDdeTVr3jR4peY9jDpiqYV1d82vBwyV8ybl 44DyJeJ0/6GPKx1Oc35bHCk2wN2hI4co06TFNW2fARRS36Y4RlMua7HPQRG3cfG9 GXDQCr0sz3p9CLhTRxpkFztHTzWxZXokWUPiF+xnpmlzSFgUdzqjAOQBSoFFQ1oo PE0z0abrPpAHbAkOAOTrouSetRBnErxbK0ljHqwkj2cSEWtR1OQPL2PLu5ZZlkAA w6D/Htp3ai17kBA2nEDTh6TN2JZuGOb2pR2W1a1OxHisAjPCSrY3+ySDIFelRR72 M2BOsPumC7be2BFw+RxprsTPLYUKWsKXdsY85Uh7blClivCKMLbQGtfnHH+4NRuq Gn1c3ZEBQryTqX9C42GbmGEXXhIny62b1pGf9cna45p4IN1NcSqYRztd/9KO0DbW 0cARvff2vYaiebprbksCeOvBinU06wNdgHeZuGo95Sv5ZGDWH8u7c95u7lC2pK8S cb2ZPQ6oDsOLgZAPjUd5/uPyG9AEXFUljhbXq8h/BQrMO3LTPU6uSdLb0s+/Uhki VmRV74r/hoEV4DE22ZThFW7s3h1/FVmEkwH1dFwy2rqNn1Bx2Spir9kJKHG3VKJ2 CvrrXv0g4ZOXnGZ+pi9y =x5tN -----END PGP SIGNATURE----- --qOrJKOH36bD5yhNe--